The invention relates to a drilling and/or chiseling tool with a shaft having a cylindrical insertion and with at least one elongated recess open on the outer surface and free end of the insertion end. A collar is located on the shaft extending at least partially around and radially outwardly of the shaft and insertion end. The invention also relates to a tool chuck or holder of the device for a tool, constructed in accordance with the invention.
Drilling and/or chiseling devices, which have a pneumatic or a hydraulic drive are generally used to produce deep boreholes in rock. The drilling and/or chiseling tools, which are used in connection with these devices, have, for example, a hexagonally shaped insertion end for a correspondingly shaped tool chuck of the drilling and/or chiseling device. Tools are also known that have an insertion end with a plurality of oblong grooves. The grooves have an approximately trapezoidal cross-section and interact, in the tool chuck of the drilling and/or chiseling device, with strip-shaped rotationally locking bodies, which extend axially and are formed on the inner wall of the tool chuck. The axial locking of these known drilling and/or chiseling tools is accomplished by means of a shackle affixed to the device, which can be pivoted and engages a collar or the like provided on the drilling and/or chiseling tool.
For the production of deep boreholes in rock, the drilling and/or chiseling tools are subjected to high torques, which lead to increased wear, particularly in the region of the rotationally locking grooves or rotationally locking surfaces of the tool and the rotational catches of the tool chuck or holder of the drilling and/or chiseling device. The wear is increased further by the abrasive products formed during drilling and/or chiseling.
Therefore, it is the object of the present invention to eliminate these disadvantages in the state of the art and to create a drilling and/or chiseling tool with an improved service life. In this connection, the drilling and/or chiseling tool is also intended to be used in conjunction with electrically operated drilling and/or chiseling devices with an electropneumatic striking mechanism. Furthermore, for a drilling and/or chiseling device, a tool chuck or holder, which exhibits less susceptibility to wear, is to be developed.
These tasks are accomplished with a drilling and/or chiseling tool where the insertion end of the tool has a diameter of at least 18 mm and the recess in the insertion end has the form of a divided or partial circle. Advantageous variations of the invention and/or preferred examples are set forth in the dependent claims. A tool chuck or holder of a drilling and/or chiseling device, matched to the inventive drilling and/or chiseling tool, is also set forth in the dependent claims. The inventive drilling and/or chiseling tool comprises a shaft with a cylindrical insertion end having at least one axially elongated recess, which is open towards the outer surface and towards the free end of the insertion end. A collar is disposed between the shaft and the insertion end and extends at least partially around the tool and projects radially outwardly, at least partially beyond the shaft and the insertion end. The cylindrical insertion end has a diameter, which is equal to or larger than 18 mm and preferably larger than 22 mm. The at least one recess has a cross-sectional area, which extends perpendicularly to the center axis of the tool, which expands towards the outer surface of the insertion end and has the form of a divided circle or arc of a circle.
For the given large diameters of the insertion end, the drilling and/or chiseling tools of the state of the art usually have an insertion end, which is constructed as a hexagon and, at the transition to the shaft, have a revolving annular collar. On the other hand, the inventive drilling and/or chiseling tool starts out from an insertion end, which is essentially cylindrical and has at least one recess, which extends in the axial direction and is open towards the free end and towards the periphery. For reasons of symmetry and for a better introduction of force, the at least one recess has a cross-section surface perpendicular to the center axis and is essentially formed in the shape of an arc. The at least one recess serves as a rotationally locking groove. In connection with a correspondingly formed rotationally locking body in a tool chuck or holder of a drilling and/or chiseling device, the rotationally locking groove, which is present as a round groove, because of its cross-sectional shape, demonstrates less wear during the transfer of torque than do the insertion ends of the tools in the state of the art. The open structure of the round groove towards the free end of the insertion end facilitates the accurate positioning of the tool during insertion. In particular, the inventive drilling and/or chiseling tool is also prepared for use in connection with electrically operated drilling and/or chiseling devices, which demonstrate the advantageous electropneumatic striking mechanism technology and the proven drive technology of the hammer drilling devices, which are known from the state of the art and are designed for tools with insertion ends up to 18 mm and are also sold by the assignee.
In an advantageous embodiment of the invention, the recess has a radius of curvature that corresponds approximately to 0.1 to 0.35 times the diameter of the insertion end. In connection with the minimum diameter for the insertion end as indicated, the selected range for the radius of curvature of the recess formed as a rounded groove, in connection with a correspondingly shaped rotationally locking body, results in two-dimensional contact, which has an advantageous effect on the wear of the recess and/or the rotationally locking body.
In order to be able to transfer sufficiently great torques, a depth of the recess, measured in the radial direction, with reference to the outer surface amounts to approximately 50% to 100% of the radius of curvature of the recess formed as-a rounded groove, proves to be advantageous.
In a particularly practical embodiment of the inventive drilling and/or chiseling tool, the insertion end has four recesses that are arranged evenly around the circumference of the insertion end. The larger number of recesses allows the transfer of greater torques. Because of the uniform arrangement of the identically formed recesses around the circumference of the cylindrical insertion end, the tool can be inserted in four positions and only has to be rotated for a small angle, a maximum angle of approximately 90xc2x0, when being inserted into a correspondingly formed tool holder, so that the rotationally locking body or bodies can enter into the recess(es).
To ensure that, in operation, the correspondingly formed rotationally locking bodies, over their whole axial length, if possible and in every axial portion of the tool, are in two-dimensional engagement with the recesses, the locking bodies in each case advantageously have a length, which corresponds to about 2 times to about 4 times the diameter of the insertion end.
The drilling and/or chiseling tool is axially secured by means of a pivotable shackle or the like, that engages the collar in the transition region from the shaft to the insertion end. To guarantee a secure axial hold for the tool even during hard use, and so that the tool does not unintentionally fall out of the tool holder as a result of the axial impacts applied to the rear, free end of the insertion end, the outer diameter of the collar is about 1.25 times to about 1.5 times the diameter of the insertion end.
The length of the insertion end is defined by the distance of the collar from the free end of the insertion end. To create a sufficiently long length for the axial recesses, a distance of the collar from the free end of the insertion end, which amounts to about 7 times to about 9 times the diameter of the insertion end, proves to be advantageous.
A tool chuck or holder of a drilling and/or chiseling device for operation along with an inventive drilling and/or chiseling tool comprises a tool chuck with at least one roller-shaped rotationally locking body. The latter is fixed radially and axially in a groove provided in the inner wall of the tool chuck. In this connection, the groove is constructed in such a way that the at least one roller-shaped rotationally locking body can be rotated about its axis in the groove. Because of the rotatable mounting of the rotationally locking body, the entire surface of the rotationally locking body engages with the recess in the insertion end of the tool. By these means, wear phenomena are distributed over the entire surface of the rotationally locking body and its service life is extended. Advantageously, the rotationally locking body is selected so that about 30% to 47% of its largest diameter protrudes from the inner wall of the tool chuck.
In order to achieve particularly good two-dimensional contact of the at least one rotationally locking body in the recess in the insertion end of the drilling and/or chiseling tool, the radius of curvature of the at least one rotationally locking body corresponds to the radius of curvature of the recess in the insertion end.
For uniformly stressing the recesses in the insertion end of the inventive drilling and/or chiseling tool, and for transferring large torques, it is advantageous if the number of rotationally locking bodies in the tool holder advantageously corresponds to the number of recesses in the insertion end of the drilling and/or chiseling tool. In this connection, it is preferably if the rotationally locking bodies are distributed uniformly around the periphery of the inner wall of the tool chuck. For reasons of space and simple symmetry, four rotationally locking bodies, are provided.
So that every rotationally locking body remains in contact in all positions of the tool with every corresponding recess in the insertion end of the tool over as large an area as possible during operation of the drilling and/or chiseling device, an axial length for each rotationally locking body amounting to about 25% to about 70% of the axial length of a recess in the insertion end of the drilling and/or chiseling tool proves to be advantageous.
Very simple maintenance and replacement of the tool holder and, in particular, of the rotationally locking body are guaranteed owing to the fact that the rotationally locking bodies are fixed radially by a removable fixing sleeve, which can be placed on the outside of the tool chuck, facing away from the inner wall.
The invention will be explained in greater detail below, with reference to an example shown in the Figures, in the diagrammatic representation, which is not to scale.